[Intel-gfx] [PATCH] drm/i915: Apply LUT validation checks to platforms more accurately (v2)

[Ville Syrjälä]

On Tue, Jan 29, 2019 at 04:49:28PM -0800, Matt Roper wrote:
> Use of the new DRM_COLOR_LUT_NON_DECREASING test was a bit over-zealous;
> it doesn't actually need to be applied to the degamma on "bdw-style"
> platforms.  Likewise, we overlooked the fact that CHV should have that
> test applied to the gamma LUT as well as the degamma LUT.
> 
> Rather than adding more complicated platform checking to
> intel_color_check(), let's just store the appropriate set of LUT
> validation flags for each platform in the intel_device_info structure.
> 
> v2:
>  - Shuffle around LUT size tests so that the hardware-specific tests
>    won't be applied to legacy gamma tables.  (Ville)
>  - Add a debug message so that it will be easier to understand why an
>    atomic transaction involving incorrectly-sized LUT's got rejected
>    by the driver.
> 
> Fixes: 85e2d61e4976 ("drm/i915: Validate userspace-provided color management LUT's (v4)")
> References: https://lists.freedesktop.org/archives/intel-gfx/2019-January/187634.html
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
> ---
>  drivers/gpu/drm/i915/i915_pci.c          | 10 ++++--
>  drivers/gpu/drm/i915/intel_color.c       | 58 ++++++++++++++++----------------
>  drivers/gpu/drm/i915/intel_device_info.h |  2 ++
>  3 files changed, 39 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
> index 44c23ac60347..17f5a605b0b3 100644
> --- a/drivers/gpu/drm/i915/i915_pci.c
> +++ b/drivers/gpu/drm/i915/i915_pci.c
> @@ -69,9 +69,15 @@
>  #define BDW_COLORS \
>  	.color = { .degamma_lut_size = 512, .gamma_lut_size = 512 }
>  #define CHV_COLORS \
> -	.color = { .degamma_lut_size = 65, .gamma_lut_size = 257 }
> +	.color = { .degamma_lut_size = 65, .gamma_lut_size = 257, \
> +		   .degamma_lut_tests = DRM_COLOR_LUT_NON_DECREASING, \
> +		   .gamma_lut_tests = DRM_COLOR_LUT_NON_DECREASING, \
> +	}
>  #define GLK_COLORS \
> -	.color = { .degamma_lut_size = 0, .gamma_lut_size = 1024 }
> +	.color = { .degamma_lut_size = 0, .gamma_lut_size = 1024, \
> +		   .degamma_lut_tests = DRM_COLOR_LUT_NON_DECREASING | \
> +					DRM_COLOR_LUT_EQUAL_CHANNELS, \
> +	}
>  
>  /* Keep in gen based order, and chronological order within a gen */
>  
> diff --git a/drivers/gpu/drm/i915/intel_color.c b/drivers/gpu/drm/i915/intel_color.c
> index bc7589656a8f..59b8a644b218 100644
> --- a/drivers/gpu/drm/i915/intel_color.c
> +++ b/drivers/gpu/drm/i915/intel_color.c
> @@ -605,48 +605,48 @@ void intel_color_load_luts(struct intel_crtc_state *crtc_state)
>  	dev_priv->display.load_luts(crtc_state);
>  }
>  
> +static int check_lut_size(const struct drm_property_blob *lut, size_t expected)
> +{
> +	size_t len;

I'd probably just use int here. size_t makes me think it's in bytes or
something like that.

Otherwise lgtm. Either way
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> +
> +	if (!lut)
> +		return 0;
> +
> +	len = drm_color_lut_size(lut);
> +	if (len != expected) {
> +		DRM_DEBUG_KMS("Invalid LUT size; got %lu, expected %lu\n",
> +			      len, expected);
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  int intel_color_check(struct intel_crtc_state *crtc_state)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(crtc_state->base.crtc->dev);
>  	size_t gamma_length, degamma_length;
> -	uint32_t tests = DRM_COLOR_LUT_NON_DECREASING;
> +	u32 gamma_tests, degamma_tests;
>  
>  	degamma_length = INTEL_INFO(dev_priv)->color.degamma_lut_size;
>  	gamma_length = INTEL_INFO(dev_priv)->color.gamma_lut_size;
> +	degamma_tests = INTEL_INFO(dev_priv)->color.degamma_lut_tests;
> +	gamma_tests = INTEL_INFO(dev_priv)->color.gamma_lut_tests;
>  
> -	/*
> -	 * All of our platforms mandate that the degamma curve be
> -	 * non-decreasing.  Additionally, GLK and gen11 only accept a single
> -	 * value for red, green, and blue in the degamma table.  Make sure
> -	 * userspace didn't try to pass us something we can't handle.
> -	 *
> -	 * We don't have any extra hardware constraints on the gamma table,
> -	 * so no need to explicitly check it.
> -	 */
> -	if (IS_GEMINILAKE(dev_priv) || INTEL_GEN(dev_priv) >= 10)
> -		tests |= DRM_COLOR_LUT_EQUAL_CHANNELS;
> +	/* Always allow legacy gamma LUT with no further checking. */
> +	if (crtc_state_is_legacy_gamma(crtc_state))
> +		return 0;
>  
> -	if (drm_color_lut_check(crtc_state->base.degamma_lut, tests) != 0)
> +	if (check_lut_size(crtc_state->base.degamma_lut, degamma_length) ||
> +	    check_lut_size(crtc_state->base.gamma_lut, gamma_length))
>  		return -EINVAL;
>  
> -	/*
> -	 * We allow both degamma & gamma luts at the right size or
> -	 * NULL.
> -	 */
> -	if ((!crtc_state->base.degamma_lut ||
> -	     drm_color_lut_size(crtc_state->base.degamma_lut) == degamma_length) &&
> -	    (!crtc_state->base.gamma_lut ||
> -	     drm_color_lut_size(crtc_state->base.gamma_lut) == gamma_length))
> -		return 0;
> +	if (drm_color_lut_check(crtc_state->base.degamma_lut, degamma_tests) ||
> +	    drm_color_lut_check(crtc_state->base.gamma_lut, gamma_tests))
> +		return -EINVAL;
>  
> -	/*
> -	 * We also allow no degamma lut/ctm and a gamma lut at the legacy
> -	 * size (256 entries).
> -	 */
> -	if (crtc_state_is_legacy_gamma(crtc_state))
> -		return 0;
>  
> -	return -EINVAL;
> +	return 0;
>  }
>  
>  void intel_color_init(struct intel_crtc *crtc)
> diff --git a/drivers/gpu/drm/i915/intel_device_info.h b/drivers/gpu/drm/i915/intel_device_info.h
> index 957c6527f76b..7bf09cef591a 100644
> --- a/drivers/gpu/drm/i915/intel_device_info.h
> +++ b/drivers/gpu/drm/i915/intel_device_info.h
> @@ -189,6 +189,8 @@ struct intel_device_info {
>  	struct color_luts {
>  		u16 degamma_lut_size;
>  		u16 gamma_lut_size;
> +		u32 degamma_lut_tests;
> +		u32 gamma_lut_tests;
>  	} color;
>  };
>  
> -- 
> 2.14.5

-- 
Ville Syrjälä
Intel